Plexiglass Dead Front

D

dbhennessey

Member
Location
New Mexico
Occupation
Electrician
I work for a defense contractor that builds assets for various military contracts. We have to cram a lot into small spaces, so I go around with the engineers on issues such as location, size of enclosures, and other issues. We have our own fabrication department and have the capability to build things in house. An engineer purchased a 14"x6"x6" Nema 12 enclosure to house a Square D 200A 3P circui8t breaker to interrupt the load side of a 75KVA transformer. We fabricated a back plate to mount the breaker on and I suggested a Metal dead front to install in front of this breaker allowing only access to the breaker handle. The engineer decided he wanted a plexiglass dead front instead. My argument that although it makes it finger safe when you open the hinged cover to energize the breaker, It is not a good idea for a possible arc flash. Is there anything in code or anywhere else regarding this practice? I have said I will not sign off on this install.
 
H

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
dbhennessey said:
I work for a defense contractor that builds assets for various military contracts. We have to cram a lot into small spaces, so I go around with the engineers on issues such as location, size of enclosures, and other issues. We have our own fabrication department and have the capability to build things in house. An engineer purchased a 14"x6"x6" Nema 12 enclosure to house a Square D 200A 3P circui8t breaker to interrupt the load side of a 75KVA transformer. We fabricated a back plate to mount the breaker on and I suggested a Metal dead front to install in front of this breaker allowing only access to the breaker handle. The engineer decided he wanted a plexiglass dead front instead. My argument that although it makes it finger safe when you open the hinged cover to energize the breaker, It is not a good idea for a possible arc flash. Is there anything in code or anywhere else regarding this practice? I have said I will not sign off on this install.
Click to expand...
His argument may be you can IR through some "plexiglass". Or IR acrylic..

You can't IR through metal plate.
 
P

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
dbhennessey said:
The Nema 12 enclosure certainly is. what we work on is not covered by the NEC but we try to accommodate it as much as we can.
Click to expand...
NEMA type enclosures are not listed. UL type enclosures are listed. NEMA 12 looks a lot like UL type 12 but they are not listed to the NEMA 12 standard.

In any case if you replace the four you might as well get what you want out of it

I am surprised you don't build such things to UL508a standards and get them listed.
 
You must log in or register to reply here.
Top